Desert Carbon Sinks

When it comes to the carbon cycle there are still some parts of it that scientists haven’t quite figured out. For instance, the total amount of carbon that we are able to measure through plants, emissions and other naturally occurring events isn’t all the carbon on Earth. So-called carbon sinks may be the source of this missing carbon, and scientists are out to learn more about carbon sinks around the world.

Desert carbon sinks seem to hold the key to understanding the complete cycle of carbon on Earth. Deep underground aquifers hold onto bits of carbon that have been absorbed through plants and that have soaked into the ground. Scientists have recently learned that plants don’t uptake all the carbon they come into contact with; this leftover carbon might be found deep in the earth in these massive aquifers.


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Desert carbon sinks are also influenced by irrigation and agricultural practices. Plants absorb carbon dioxide in the air and release some of this carbon into the soil, where it can eventually flow into an underground stream or stored in a desert aquifer. As desert aquifers are located very deep under the surface of the Earth this carbon is unable to be released back into the atmosphere and therefore stays in its new underground home.

Scientists are now working to locate many of these underground aquifers which exist all over the world. Knowing how much carbon is leaked into these aquifers from plants and agriculture could be a major step in understanding the missing carbon sinks. Additionally, more information about the carbon cycle could help environmental scientists create a more detailed projection of how the missing carbon will affect the environment in the future.

Scientists followed the journey of water through the Tarim Basin from the rivers at the edge of the valley to the desert aquifers under the basin. They found that as water moved through irrigated fields, the water gathered dissolved carbon and moved it deep underground. Credit: Yan Li

Scientists followed the journey of water through the Tarim Basin from the rivers at the edge of the valley to the desert aquifers under the basin. They found that as water moved through irrigated fields, the water gathered dissolved carbon and moved it deep underground.
Credit: Yan Li

Putting together the many pieces that influence carbon’s cycle through the world is complicated. Many different factors influence the journey that eventually can result in carbon being stored in desert carbon sinks. Scientists have to determine how much carbon is created by man and natural sources, how much carbon various plant species in different climates use, and how much carbon is dissolved and transported via waterways. The influence of desert irrigation is another important factor that has already seriously altered the balance of carbon on Earth. Past projections about a carbon budget may also need to be looked at again as more information about desert carbon sinks become known.

Schematic diagram of DIC (dissolved inorganic carbon) leaching and transport in a closed arid basin: Tarim Basin as an example. From Li et al, 2015.

Schematic diagram of DIC (dissolved inorganic carbon) leaching and transport in a closed arid basin: Tarim Basin as an example. From Li et al, 2015.

As always, more research into carbon sinks will help pave the way for an increased understanding of how desert carbon sinks really influence the global carbon cycle. Current studies are already shedding valuable light on the topic and will hopefully allow for more research in the area. Knowing where carbon sinks are located and facts about them could help regulate the global carbon budget and allow for new projections about Earth’s environmental future to be created.

Reference

“Carbon sink” detected underneath world’s deserts – AGU News

Li, Y., Wang, Y. G., Houghton, R. A., & Tang, L. S. (2015). Hidden carbon sink beneath desert. Geophysical Research Letters. Retrieved from http://onlinelibrary.wiley.com/doi/10.1002/2015GL064222/full?campaign=wlytk-41855.5282060185